Using nfc shield with sd breakout (SPI conflict)

Using Arduino Project Guidance
1

Ok,

I'm using the seed studio pn532 nfc shield stacked on my mega. I also have an SD SPI breakout board (cheap one off ebay).

SD is wired to the SPI pins on mega (50-52) and CS is pin 4. NFC shield CS is default (10).

I'm stuck on how to get them to work. I cannot even have both plugged in at one time. I've tried setting pin 4 to HIGH when I use the NFC shield but that doesn't work. I'm using the standard PN532 library (https://s3.amazonaws.com/linksprite/Shields/NFC_shield/PN532_SPI.zip) and SD library.

I'm basically trying to combine loads of separate sketches I've made into one program, I'd post the code I have so far but its mainly to do with other stuff, but feel free to ask for it if you think it will help.

Thanks,

Tom

2

Anyone help??

I've tried following this - https://www.circuitsathome.com/mcu/running-multiple-slave-devices-on-arduino-spi-bus-data-formats

Still won't work.

3

also tried using this library - GitHub - jmgjmg/PN532: Arduino Library for Seeedstudio NFC Shield based on NXP PN532 chip

getting desperate now I have no clue what to do =( =(

4

For future reference, the SD card breakout I bought (catalex v1.0) does not release the MISO pin when CS is High, meaning it is the only device that can be used on the SPI bus.

I am now using a software SPI implementation in the adafruit SD library, which works perfectly.

Sorry about the spam.

Tom

5

Thanks,
Useful information . I was able to use the bare RC522 shield that is connected on the Catalex board operational without using ISCP connector but same RC522 shield connected on Catalex did nothing.
Give it a retry with ISCP connector connected but still nothing. Not clear how pins on Catalex are corrected.